First (sniffing) part of the wrapper

Updated Makefile.am and .gitignore

.gitignore

@@ -18,6 +18,7 @@ INSTALL
 # build
 *.o
 wrapsix-dnsproxy
+wrapsix-wrapper
 
 # debug
 core

src/Makefile.am

@@ -1,2 +1,3 @@
-sbin_PROGRAMS = wrapsix-dnsproxy
+sbin_PROGRAMS = wrapsix-dnsproxy wrapsix-wrapper
 wrapsix_dnsproxy_SOURCES = dnsproxy.c
+wrapsix_wrapper_SOURCES = wrapper.c wrapper.h

src/wrapper.c

@@ -0,0 +1,119 @@
+/*
+ *  WrapSix
+ *  Copyright (C) 2008-2010  Michal Zima <xhire@mujmalysvet.cz>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as
+ *  published by the Free Software Foundation, either version 3 of the
+ *  License, or (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <arpa/inet.h>		/* inet_pton */
+#include <linux/if_ether.h>	/* ETH_P_ALL */
+#include <net/if.h>		/* struct ifreq */
+#include <netpacket/packet.h>	/* struct packet_mreq, struct sockaddr_ll */
+#include <netinet/in.h>		/* htons */
+#include <net/ethernet.h>	/* ETHERTYPE_* */
+#include <stdio.h>
+#include <string.h>		/* strncpy */
+#include <sys/ioctl.h>		/* ioctl, SIOCGIFINDEX */
+#include <unistd.h>		/* close */
+
+#include "wrapper.h"
+
+#define INTERFACE	"eth0"
+#define BUFFER_SIZE	65536
+
+int process(char *packet);
+
+int main(int argc, char **argv)
+{
+	struct ifreq		interface;
+	struct packet_mreq	pmr;
+
+	struct sockaddr_ll	addr;
+	size_t			addr_size;
+
+	int	sniff_sock;
+	int	length;
+	char	buffer[BUFFER_SIZE];
+
+	/* initialize the socket for sniffing */
+	if ((sniff_sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL))) == -1) {
+		fprintf(stderr, "[Error] Unable to create listening socket\n");
+		return 1;
+	}
+
+	/* get the interface */
+	strncpy(interface.ifr_name, INTERFACE, IFNAMSIZ);
+	if (ioctl(sniff_sock, SIOCGIFINDEX, &interface) == -1) {
+		fprintf(stderr, "[Error] Unable to get the interface\n");
+		return 1;
+	}
+
+	/* set the promiscuous mode */
+	memset(&pmr, 0x0, sizeof(pmr));
+	pmr.mr_ifindex = interface.ifr_ifindex;
+	pmr.mr_type = PACKET_MR_PROMISC;
+	if (setsockopt(sniff_sock, SOL_PACKET, PACKET_ADD_MEMBERSHIP, (char *) &pmr, sizeof(pmr)) == -1) {
+		fprintf(stderr, "[Error] Unable to set the promiscuous mode on the interface\n");
+		return 1;
+	}
+
+	/* sniff! :c) */
+	for (;;) {
+		addr_size = sizeof(addr);
+		if ((length = recv(sniff_sock, buffer, BUFFER_SIZE, 0)) == -1) {
+			fprintf(stderr, "[Error] Unable to retrieve data from socket\n");
+			return 1;
+		}
+
+		process((char *) &buffer);
+	}
+
+	/* clean-up */
+	/* unset the promiscuous mode */
+	if (setsockopt(sniff_sock, SOL_PACKET, PACKET_DROP_MEMBERSHIP, (char *) &pmr, sizeof(pmr)) == -1) {
+		fprintf(stderr, "[Error] Unable to unset the promiscuous mode on the interface\n");
+		/* do not call `return` here as we want to close the socket too */
+	}
+
+	/* close the socket */
+	close(sniff_sock);
+
+	return 0;
+}
+
+int process(char *packet)
+{
+	struct s_ethernet	*eth;		/* the ethernet header */
+	char			*payload;	/* the IP header + packet payload */
+
+	/* parse ethernet header */
+	eth     = (struct s_ethernet *) (packet);
+	payload = packet + sizeof(struct s_ethernet);
+
+	switch (htons(eth->type)) {
+		case ETHERTYPE_IP:
+			printf("[Debug] HW Protocol: IPv4\n");
+			return -1;
+		case ETHERTYPE_IPV6:
+			printf("[Debug] HW Protocol: IPv6\n");
+			return -1;
+		case ETHERTYPE_ARP:
+			printf("[Debug] HW Protocol: ARP\n");
+			return -1;
+		default:
+			printf("[Debug] HW Protocol: unknown [%d/0x%04x]\n",
+			       htons(eth->type), htons(eth->type));
+			return 1;
+	}
+}

src/wrapper.h

@@ -0,0 +1,39 @@
+/*
+ *  WrapSix
+ *  Copyright (C) 2008-2010  Michal Zima <xhire@mujmalysvet.cz>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as
+ *  published by the Free Software Foundation, either version 3 of the
+ *  License, or (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef WRAPPER_H
+#define WRAPPER_H
+
+/* MAC address structure */
+struct s_mac_addr {
+	unsigned char		a;
+	unsigned char		b;
+	unsigned char		c;
+	unsigned char		d;
+	unsigned char		e;
+	unsigned char		f;
+} __attribute__ ((__packed__));
+
+/* Ethernet header structure */
+struct s_ethernet {
+	struct s_mac_addr	dest;	/* 48 b; destination host (MAC) address */
+	struct s_mac_addr	src;	/* 48 b; source host (MAC) address */
+	unsigned short		type;	/* 16 b; IP/ARP/RARP/... */
+} __attribute__ ((__packed__));
+
+#endif /* WRAPPER_H */